Draft-producing device.



PATENTED JULY 7, 1903.

C. SCOTT-SNELL.

DRAFT PRODUCING DEVICE.

APPLICATION FILED SEPT. 8, 1902.

5 SHEETS-SHEET 1.

N0 MODEL.

PnERs cu, mum-mun. wnsuwcrm PATENTED JULY 7, 1903.

C. SCOTT-SNELL.

DRAFT PRODUCING DEVICE.

APPLICATION FILED SEPT. s, 1902.

5 SHEETSSHEET 2.

HO MODEL.

\lllllilll'llllll'llLIl-Illlll CiarZcs 30066-52650, I

m: mamas Firms :0, wm'um'uov WASHINGTON u c No. 733,839. PATENTED JULY7, 1903. G. SCOTT-SNELL. DRAFT PRODUCING DEVICE.

APPLICATION FILED SEPT. 8 1902.

N0 MODEL. 5 SHEETSSHEET 3.

I 5 I i I l Z 5 7' I i i I El 2 a 7, 5 J 8 m s l No. 733,339. PATENTEDJULY 7, 1903.

. SGOTT- ELL.

PRO G DEVICE;

TION saw. a, 1902.

I0 KODEL.

6 SHEETS-SHEET 4.

PATENTED JULY 7, 1903.

C. SCOTT-SNELL. I DRAFT PRODUCING DEVICE.

APPLICATION FILED SEPT. 8. 1902.

5 BHEETS-SHEET 5.

NO MODEL.

w mm

we NGRRvS PtYLRS an r UNITED STATES Patented July 7, 1903.

PATENT OFFICE.

DRAFT-PRODUCING DEVICE.

SPECIFICATION forming part of Letters Patent No. 733,339, dated July 7,1903'. 0riginal application filed October 28, 1901, Serial No. 80,355.Divided and this application filed September 8, 1902'. Serial To allwhom it may concern.-

Be it known that I, CHARLES SCOTT-SNELL, a subject of the King of GreatBritain and Ireland, residing at Culver Park, Saltash, in the county ofCornwall, England, have invented a certain new and usefulDraft-Producing Device, (for which I have made application for LettersPatent in Great Britain, dated April 4, 1901, and numbered 7,154; inFrance, No. 317,732, dated January 13, 1002, and in Germany, No. S.15,915, dated January 15, 1902,) of which the following is aspecification.

This application is a division of my application, Serial No. 80,355,filed October 28, 1901, and patented under date of September 30, 1902,No. 710,370.

My invention relates to means for producing forced or induced draft insteam-boilers and other apparatus in which solid, liquid, or gaseousfuel is burned under force or induced draft, and has for its object toeffect such increased draft in a more economical manner. than hitherto.

My invention consists generally in means for effecting forced or induceddraft by utilizing waste heat from combustion of fuel in the boiler orother furnace, the waste heat operating upon the elastic fluid toproduce alternate expansion and contraction in such a manner that aquantity of the elastic fluid is delivered either into the waste-gasflue in such a Way as to eifect induced draft or into the air-inlet ofthe furnace in such a way as to efiect forced draft.

My invention further consists in details for carrying this generalprocess into efiect.

In carrying my invention into effect, generally as applied to asteam-boiler, I utilize the heat in the products of combustion afterthey have effected their primary purpose, such as raising steam in aboiler, and are on their way to be discharged into the atmosphere. Thewaste heat when brought into contact with cold air tends to produceexpansion of the air, and if the air be within a closed vessel, so thatthe expansion is wholly or partially prevented, a rise of pressureensues. The air under pressure so produced may be discharged into theuptake leading into the funnel to induce a draft or into the ash-pit orother suitable place, so that it will by its pressure increase the rateof combus- (No model.)

tion in the furnace by effecting what is known as forced draft. In theforceddraft arrangement the air may be heated before entering thefurnace by passing it into contact with surfaces heated by the wastegases. In order to maintain the continuity of supply of air underpressure, I cause the remaining volume of heated air within theinclosedvesseltofallintemperature. Thefallin temperature may be effectedby bringing this volumeinto contact with a surface sufficiently lower intemperature than the source of heat, or it may be effected by cuttingoff the suppl) of heat acting upon the inclosed air. In either case thefall must be enough to produce a partial vacuum within the vessel andcause an influx of more air. The supply of fresh air is drawn in througha check-valve to prevent escape when the air expands under the influenceof heat, and in order to prevent the heated air already delivered frombeing drawn back a second check-valve is fitted to the eduction-outlet.

The alternate heating and cooling of the air (in order to maintaincontinuity of supply) may be produced by accumulating such air incontact with a surface heated by the products of combustion, such as thesurface of the uptake or other portion of the system traversed by theheated products, and afterward against a surface cooled by awaterjacket, or the same result may be produced by shielding the saidheated surface and uncovering the previously-shielded cool surface toproduce condensation and then afterward shielding the cooled surface anduncovering the heated surface to produce pressure.

It willbe obvious that in applying myinvention to gas-producers the wallof the producer may form the hot side of my apparatus.

In the accompanying drawings, Figure 1 is a sectional elevation of oneform of my invention as applied to a marine boiler, the section beingtaken on the lineA A of Fig. 2. Figs. 2 and 2 are sectional end views ofthe same on the line B B and C C, respectively, of Fig. 1, showing byarrows the course of the air during the air-suction stroke. Figs. 3 and3 are similar views of the same, but showing by arrows the course of theair during the discharge movement of the displacer. Fig. 4 is adiagrammatic view of another form of my invention as applied to aCornish or land boiler; and Fig. 5 is a longitudinal section, and Fig.(5 a cross-section, of this blower on an enlarged scale.

In carrying my invention into effect according to one modification asapplied to a marine steam-boiler I form an air-chamber 6 against theouter surface of the boiler-uptake a by means of plates 19 0 (Z and thenecessary side plates. (Not shown.) Against the wall d of theair-chamber I construct a water-tank f, extending from the top of theair-chamber to within a short distance of its bottom. In this way oneside of the air-chamber is maintained at a high temperature by the gasespassing up the uptake, and the other side is kept cool by thewater-jacket. Within the air-chamber c I suspend or pivot on ahorizontal axis a vertical displacer 6, preferably wedge-shaped incross-section. The displacer is capable of swinging on its axis like apunka When operated by a lever in any suitable manner. In order toprevent the transmission of heat from the hot side of the displacer tothe cool side thereof, the displacer may be formed hollow, or it may beconstructed of any suitable heat-insulating material. The plate 11,forming the bottom of the air-chamber e, is carried along to meet acontinuation of the front wall g of the water-tankf, so as to form anair-tight compartment m under the Watertank. I divide this compartmentinto a number of smaller compartments or boxes 0 and g by means ofpartitions n, as seen in Fig. 1. Openings controlled by valves p in thewall (Z permit direct commu nication between every box 0 and the bottomof the cool side of the air-chamber, and permanent communication betweeneach of these boxes 0 and the top of the hot side of the air-chamber iseffected by means of the tubes 7', which lead from the bottom of theplate Z), through the uptake-wall a, and into the upper part of theair-chamber. The boxes q communicate with the bottom of the hot side ofthe air-chamber through the tubes 3, which are provided with valves i,opening into the boxes q. The cooled upper portion of the air-chamberand the boxes (1 are also connected together by tubes u, passing fromthe top of thelatter through the water-tank to the top of theair-chamber.

The supply of fresh air to the air-chamber is obtained by means of aduct'11, which passes through the water-tank and is provided with anon-return valve 10. The aiwductv is fed through a pipe 2; (aside 1' ofwhich is shown dotted in Fig. 2) from a suitable open space. Alift-valve at on the top of the air-chamber permits air to be dischargedinto a reservoir or compartment y, whence it passes bya pipe 2 (seeFigs. 1, 2, and 3) into the uptake to cause a draft. manner when thedisplacer 2' is moved from its extreme left-hand position to its extremeright-hand position. The hot air in the diminishing space between thehot wall a and the displacer is delivered through the pipes s, valves 1,and pi pes it into the cool space of The blower operates in this theairchamber. In passing through the pipes to, however, the displaced airis cooled and reduced in volume, so that a supply of fresh air is neededto fill the cool space of the chamber with air at atmospheric pressure.This air is automatically supplied by suction through the valve 20 andair-duct '0.

In Fig. 2 the course of the air expelled from the hot side of thechamber to the cooled side is shown by the arrows 2 2 and the course ofthe fresh air drawn in to the cool side is shown by the arrows 8 3.

When the displacer moves from its extreme right-hand position to itsextreme left-hand position, the air which filled the cool space of theair-chamber c is displaced through the valvesp and pipes r into theheated side of the chamber 6, as indicated by the arrows 4: 4 in Fig. 3.By passing through the hot pipes r and by coming in contact with the hotwalla of the chamber 6 the air becomes highly heated, thus causing arise in pressure and producing a considerable volume of air in excess ofthat required to lillthe space between the displacer 't' and the hotwall a at atmospheric pressure. This surplus air lifts the valve 00 andthen escapes into the compartment y, whence it passes through the pipe zand blows through an upwardly-directed nozzle 5, situated in the uptakeof the boiler. In this manner an air-blast is produced which inducesstrong draft in the funnel or smokestack of the boiler. The nozzles 5are fitted with conical mantles or rings 6 to increase the effectivework of the blast upon the furnace-gases. The heat passing away in theproducts of combustion is thus caused to increase the draft in theboiler-furnace.

I may arrange a number of air-chambers and water-tanks one aboveanother, as shown in Figs. 1 to 3, the latter being connected togetherby suitable pipes 7, as shown in Figs. land 3, and I may so operate thedisplacers that one shall be delivering air to the nozzle while theother is drawing in a fresh supply of air. In this manner a continuousblast of air is maintained in the uptake.

It is obvious that my blowers may be arranged in many different wayswithout-departing from my invention. I may, for instance, place twoair-chambers side by side or one on each side of the boiler-uptake,where the latter is suitable for such an arrangement, and I may in eachcase operate the displacers alternately, so as to produce a continuousblast in the uptake. The swinging of the displacers may be positively orautomatically effected by anysuitable means; but I prefer to usepositively-acting levers h and connecting-rods 1, (shown by full linesin Fig.1 and by dotted lines in Figs. 2 and 2%) operated by a smallsteam -engine for this purpose.

In applying my invention to land boilers, as shown in Figs. 4 and 6, Iprovide a circular metal casing formed in two portions 8 and 9, boltedor otherwise secured together.

IIO

The casing is sunk into the flue between the boiler and the smoke-stack10, so that most of the outside surface of the portion 8 is in directcontact with the hot gases in the flue, and is consequently maintainedat a high temperature. The upper portion 9 forms part of a tank 12,containing water, which covers the top of the casing and keeps it cool.Ooncentrically within this casing I arrange a hollow rotatable drum 14,preferably constructed of thin sheet metal and secured to a hollow shaft13. The drum is of sucha length as to leave only a small clearancebetween its ends and the ends of the casing, while its diameter is onlyslightly smaller than the inside of the casing. The drum is constructedwith a recess along its surface parallel to its axis, the width of therecess being about equal to that part of the circumference of the casingwhich is in contact with the flue-gases. The air-space 15,formed betweenthe recessed part of the drum and the inside of the casing, is by therotation of the drum alternately brought opposite to the hot part of thecasing and opposite the water-cooled part.

The hollow shaft 13 is supported at each end by bearings 16, and theends of the casing are attached to projections 17, formed on thesebearing-blocks. One end of the shaft 13 is closed and carries abelt-pulley 20, operated by a suitable motor, whereby the shaft and drum are rotated within the casing. The other end of the hollow shaft isled into a valve-chest 18, having a suction-valve 19 and adelivery-valve 21. This valve-chest is provided with a stuffing-box 22to prevent the escape of air, and it may be secured to a firm base inany suitable manner.

The air-space 15 is in direct communication with the hollow shaft bymeans of one or more pipes 23, fixed to the drum and the shaft, and thedrums may be stiffened by stays 27,placed diametrically opposite thepipes 23.

The operation of this blower is as follows: When the drum is in theposition shown in Figs. 5 and 6, with the air-space adjacent to the hotsurface of the casing, the air expands and blows through the pipes 23and hollow shaft 13 into the valve-chest 18,when it passes by thedelivery-valve 21 and a service-pipe 24 to the smoke-stack, in themanner hereinbefore described with reference to Figs. 2 to 3 and asshown in Fig. 4. As the drum rotates the air-space 15 is brought aroundinto contact with the cooled plate of the watertank, thereby diminishingthe pressure of air in the space 15 and causing a suction of air throughthe air-supply pipe 25, suction-valve 19, hollow shaft 13, and pipes 23into the airspace 15. Further rotation of the drum again brings theair-space into contact with the hot surface of the casing, therebycausing the air to expand, when the operations described above recur.

The water-tank may be provided with inlet and outlet pipes for effectingcirculation of the cooling-water.

Any desired number of blowers may be employed, and by arranging theirair-spaces to be in the heating positions at different times in relationto one another a continuous blast of air may be produced.

Continuity of the blast may be effected when only one blower is employedby discharging the air into a reservoir of suitable capacity andwithdrawing the air therefrom at a constant pressure.

It is obvious that instead of delivering the air-blast into the smokestack or fine to induce a draft it may be blown in a highlyheatedcondition into a closed ash-pit or firegrate to produce what is known asforced draft.

It will be obvious that my invention may equally Well be applied in orin connection with gas-producers and other analogous apparatus.

Having now described my invention, what I claim as new, and desire tosecure by'Letters Patent, is-

1. An air-forcing device comprising a body with means for heating it anda body with means for cooling it, an air-container and means forbringing the air contained in said container alternately in contact withthe surfaces of said bodies, inlet and outlet pas-' sages for saidcontainer and valves controlling said passages, substantially asdescribed.

2. An air-forcing device comprising a body with means for heating it anda second body with means for cooling it, an air-container, means forbringing the air in said air-container alternately in contact with saidheated and cooled bodies, inlet and outlet passages for said container,valves controlling said passages, and a heat-insulating displacerwhereby conduction of heat from the hot side of said container to thecool side thereof is prevented, substantially as described.

3. Au air-forcing device comprising a cylindrical casing, means forheating part thereof by waste gases, a water-cooling jacket for coolinganother part, an air-container within said casing, a revoluble airdisplacer also within said casing and Valve-controlled air inlet andoutlet passages for said container, substantially as described.

4. An air-forcing apparatus comprising a cylindrical casing, means forheating part thereof by waste gases, at water-cooling jacket for coolinganother part, a revoluble drum within the casing, a chamber formed inthe circumference of said drum, a hollow shaft within said drum, pipesconnecting said shaft with said chamber, and valve-controlled air inletand outlet passagesfor said hollow shaft, substantially as described.

In witness whereof I have hereunto set my hand in presence of twowitnesses.

CHARLES SCOTT-SNELL.

